Pipe wrenches



1959 1... B. SHERMAN 2, 3,

PIPE WRENCHES v Filed March :5, 1958 INVENTOR. L. B. Sherman,

BY {ML 19% W ATTORNEY.

United States Patent O" This invention relates to tools for gripping and handling pipe and like objects, and more particularly to dies for use in tongs commonly employed in the rotary drilling of oil wells.

It is the practice to provide rotary tongs with removable rectangular shaped inserts called dies. Ordinarily, each die is provided with parallel, longitudinally extending ridges or lands which are sharp and serve as teeth which bite the pipe when the jaws of the tongs are applied to the pipe.

It is an object of the present invention to provide tong dies which are superior to those heretofore used for gripping pipe or the like in which the teeth thereon are curved and follow the paths of concentric circles, the results being that a greater number of teeth are brought into contact with the pipe, so that a better grip is established while bringing about a reduction in the fatigue failures of pipe, and also providing better self cleaning action on the dies themselves.

Other objects and advantages of the invention will be apparent from the following description of the preferred embodiment of dies, taken in connection with the accompanying drawings, in which:

Fig. 1 is a plan view of a die constructed in accordance with the invention;

Fig. 2 is a view in side elevation of the die of Fig. 1;

Fig. 3 is an end view of the die of Fig. 1;

Fig. 4 is a perspective view of the die of Figs. 1, 2 and 3;

Fig. 5 is a perspective view of a segment of a rotary tong in which dies constructed as illustrated in Figs. 1 to- 4 are incorporated.

Referring to the drawings in detail, it will be seen that a die constructed in accordance with the present invention may consist of a block of steel of generally rectangular shape but being an isosceles trapezoid in transverse crosssection.

One surface of the block 10 is provided with a number of sharp ridges to form teeth 11. The teeth 11 are cut on a curved pattern, all being disposed along segments of the circumferences of concentrical circles, the diameters of which are somewhat greater than the longitudinal dimension of the block 10. As a result, the teeth 11 have long sweeping edges extending lengthwise of the block 10 with all the edges being in the same plane and all having a circular path. Accordingly, when the block 10 is placed alongside a cylinder, such as a piece of pipe, with the longitudinal dimension of the block parallel with the axis of the cylinder and the surface in which the teeth 11 are cut tangent to the cylinder, several of the teeth 11 will touch the cylinder and cross the longitudinal line of contact between the block and the cylinder.

The dies 10 may be mounted in a conventional manner in a tong like that illustrated in Fig. 5. The tong illustrated is of the type which is widely used for handling casing, drill pipe and tubing in the drilling of oil wells. It has a handle 12 and jaws 13 and 14 which are linked together through pivot pins 15. A latch 16 is adapted to hold the jaws in proper position to contract and grip pipe 2,873,636 Patented Feb. 17, 1959 when the tongs are caused to encircle the pipe and torque is applied by means of the handle.

As illustrated in Fig. 5, the dies 10 of the present invention are mounted in dove-tails in the jaws 13 and 14, there being two dies in each jaw. The mounting is such that the longitudinal dimension of each die is parallel to the axis of the pipe which is to be gripped by the jaws, so that the teeth 11 extend largely in the same general direction as that of the axis of the pipe.

The use of dies having teeth of the particular configuration described above has been found to result in marked operational improvement over dies heretofore available. It will be readily apparent that only a very small portion of any one tooth may be said to have an edge substantially parallel to the axis of the pipe. Most of the biting edges of the teeth may be said to be disposed so as to extend partly crosswise of the pipe.

The construction of conventional tongs is such that until torque is applied through the handle 12, the jaws 13 and 14 do not grip the pipe even though the tongs encircle the pipe with the latch 16 engaged. In this position, the inside diameter between the jaws is slightly greater than the outside diameter of the pipe. A-s torque is applied, a large mechanical advantage is employed to decrease the inside diameter of the jaws and cause the dies to bite into the pipe.

With ordinary dies, having straight, parallel, longitudiice nally extending ridges serving as teeth, only a few of the teeth actually take part in the bite.

With the dies of the present invention, on the other hand, due to the circular configuration of the teeth 11, there are a number of teeth within the influence of the reduced diameter of the jaws as the torque is applied, and so there are a number of teeth which take part in the bite, no matter what lateral position the individual dies may be in when the reduction in diameter of the jaws is brought about. The dies thus have longer life as well as greater gripping action, there being less wear on each tooth and less penetration of each tooth into the surface of the pipe.

Not only are the dies of the present invention so designed as to reduce the amount of penetration of the teeth into the pipe during the biting action, but they are also so designed as to avoid the making of longitudinally extending, straight line scores or incisions in the pipe during the application of torque to the pipe. Pipe subjected to high fluid pressure has a tendency to split along a line parallel to its axis. Any scoring along such a line is more damaging to pipe than scoring which encircles or spirals along the pipe. The dies of the present invention are thus less harmful to the pipe than those of conventional design.

It has also been found that the dies of the present invention have a greater degree of self cleaning action than those of the prior art.

It is to be understood that some variation may exist in the shape of the teeth of the dies of the present invention,

and that some changes may be made without departing from the spirit of the invention or the scope of the annexed claims.

I claim:

1. A rotary tong having jaws adapted to be brought into engagement with pipe to apply torque to the pipe, each of said jaws being provided with a plurality of dies, each die consisting of a rectangular metal block, the dies being so mounted in the jaws as to have their longitudinal dimensions parallel with the axis of the pipe, each die having a number of sharp ridges on its gripping surface adapted to serve as teeth to bite into the pipe, said ridges being curved and concentric with respect to each other.

2. A rotary tong as defined in claim 1 in which the ridges on each die are disposed along the circumferences of circles all of which are of somewhat greater diameter than the longitudinal dimension of the block, so that the References Cited in the file of this patent UNITEDfsi Esf TENTs v 1,522,804} Carlson Jan. 13-, 1925 4 Baash Nov. 9, 1937 Wi1son' Aug. 1, 1950 Weiss May 13, 1952 Barnard Sept. 9, 1952 Woolley Oct. 11, 1955 St. Pierre Aug. 28, 1956 

